For Wavelength-Division Multiplexed (WDM) Passive Optical Network (PON) implementations, such as gigabit passive optical network (GPON), it is generally accepted that it is desirable for the Optical Network Units (ONUs) to have tunable downstream receivers and tunable upstream lasers so that so-called ‘colorless’ ONUs can be deployed and the inventory complexity implied by colored ONUs can be avoided. As understood by one of skill in the art, colorless ONUs refer to ONUs that are not fixed to a specific wavelength, whereas colored ONUs are configured for a specific wavelength.
While costs have dropped for both tunable receivers and lasers, they still remain significantly more expensive than fixed optical components. In addition, tunable receivers and lasers also suffer from temperature effects which may make it difficult to maintain precise wavelength tuning. Furthermore, lasers used in burst mode suffer from short term wavelength changes from the beginning of the burst until the wavelength stabilizes due to the abrupt injection of current from an off-burst to an on-burst state. Thus, precise tunable optical components are expensive and, if they need to operate in an environment with a wide temperature range, may not even be feasible. However, in order to implement some systems, such as Next Generation (NG)-PON2, low cost precision, tunable ONU optics are desired. NG-PON2 uses a combination of Time Division Multiple Access (TDMA) and WDM which has also been referred to as TWDM-PON. There is currently no market solution to this problem and it is currently an impediment to implementing NG-PON2. In other words, there is no economically feasible solution currently available to provide low cost precision, tunable ONU optics.